172 SCIENCE AND IMMORTALITY 



melted ; but it seems also quite certain that in 

 many cases a large quantity of debris must be shot 

 forth in all directions, much of which may have 

 experienced no greater violence than individual 

 pieces of rock experience in a landslip or in blast- 

 ing by gunpowder. Should the time when this 

 earth comes into collision with another body, 

 comparable in dimensions to itself, be when it is 

 still clothed as at present with vegetation, many 

 great and small fragments carrying seed, and 

 living plants, and animals would undoubtedly be 

 scattered through space. Hence, and because we 

 all confidently believe that there are at present, 

 and have been from time immemorial, many 

 worlds of life besides our own, we must regard it 

 as probable in the highest degree that there are 

 countless seed-bearing meteoric stones moving 

 about in space. If at the present instant no life 

 existed upon this earth, one such stone falling 

 upon it might, by what we blindly call natural 

 causes, lead to its becoming covered with vegeta- 

 tion." 



Arrhenius has suggested a modification of this 

 meteoric theory. He suggests that living particles, 

 the molecular combinations that exhibit the 

 phenomena of life, are drifting about everywhere 

 in space, under the pressure of solar radiation. 

 He supposes that such light germs of life would 



